Q.Excretory waste of birds and reptitles are

Step 1. Different animal groups excrete nitrogenous waste in different chemical forms depending on their water needs - ammonia (very water-costly, seen in fully aquatic animals), urea (moderately water-costly, seen in the frog), or uric acid (very water-conserving, semi-solid).

Step 2. Birds such as the pigeon are described as excreting waste as uric acid, discharged as a semi-solid mass without a urinary bladder - a strategy called uricotely that conserves water and reduces the weight the bird has to carry.

Step 3. Reptiles share this same uricotelic strategy for the same water-conserving reason, which is why the two groups are grouped together in this question. …

Match the excretory strategy (uricotely) shared by birds and reptiles, contra …

• Confusing the bird/reptile uric-acid strategy with the frog's urea-based (ureotelic) excretion covered earlier in the chapter. …